debounce.py

samp = [1 ,1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1]
state = 1 
db0 = 0 
db1 = 0 
print("samp     = button state               0 is pressed")
print("delta    = samp ^ state               difference between sample and state")
print("db0      = ~(db0) & delta             first bit of 2 bit counter")
print("db1      = (db1 ^ db0) & delta        second bit of 2 bit counter")
print("changes  = ~(~delta | db0 | db1)      if a change has happened")
print("state    = state ^ changes            state of the debouncer")
print("-----------")
print("{:5} {:5} {:5} {:5} {:5} {:5}".format("samp", "delta", "db0", "db1", "chngs", "state"))
for s in samp:
    delta = s ^ state
    db1 = (db1 ^ db0 ) & delta
    db0 = ~(db0) & delta
    changes = ~(~delta | db0 | db1)
    state ^= changes
    print("{:5} {:5} {:5} {:5} {:5} {:5}".format(s, delta, db0, db1, changes, state))

samp     = button state               0 is pressed
delta    = samp ^ state               difference between sample and state
db0      = ~(db0) & delta             first bit of 2 bit counter
db1      = (db1 ^ db0) & delta        second bit of 2 bit counter
changes  = ~(~delta | db0 | db1)      if a change has happened
state    = state ^ changes            state of the debouncer
-----------
samp  delta db0   db1   chngs state
    1     0     0     0     0     1
    1     0     0     0     0     1
    1     0     0     0     0     1
    1     0     0     0     0     1
    1     0     0     0     0     1
    0     1     1     0     0     1
    0     1     0     1     0     1
    0     1     1     1     0     1
    0     1     0     0     1     0
    0     0     0     0     0     0
    0     0     0     0     0     0
    1     1     1     0     0     0
    1     1     0     1     0     0
    1     1     1     1     0     0
    0     0     0     0     0     0
    0     0     0     0     0     0
    1     1     1     0     0     0
    1     1     0     1     0     0
    0     0     0     0     0     0
    0     0     0     0     0     0
    0     0     0     0     0     0
    1     1     1     0     0     0
    1     1     0     1     0     0
    1     1     1     1     0     0
    1     1     0     0     1     1
    1     0     0     0     0     1
    1     0     0     0     0     1
    1     0     0     0     0     1
    1     0     0     0     0     1